Twist Rates in AR-15 Rifles
I recently had a customer e-mail us asking a question about Twist Rates in AR-15 rifles. Here was the response I provided!
Question: What is the difference between 1:7” & 1:9” AR-15 barrels?
Answer: The difference between a 1:7″ Twist Rate barrel and a 1:9″ Twist Rate barrel is how fast the bullets will be spinning when leaving the barrel. When people talk about “Twist Rate” and reference difference numbers, they’re stating that when a bullet travels 7 inches down this barrel, it will make one full revolution or spin. The reason why this matters is heavy bullets need a faster twist rate to stabilize (basically group worth a darn on paper) while light bullets do not need such a fast twist rate. Think of it like throwing a football when we were kids. If you wanted to throw a heavy, oversized football really far, you needed to throw a fast perfect spiral to get it to your buddy. Then, if you grab a little football you could just throw with all your might and the spiral didn’t have to be as fast to get to your friend. Long story short, a 1:7″ Twist Rate barrel shoots heavier grain weight bullets more effectively (55-69 Grain); whereas, a 1:9″ Twist Rate barrel shoots lighter grain weight bullets well (50-62 Grain).
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